Reducing and enlarging machine for draftsman and designers



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C. H. WROBEL GT4/2L .H PVEOBEL,

July 14, 1953 REDUCING AND ENLARGING MACHINE FOR DRAETSMAN AND DESIGNERS Filed Feb. 6. 1952 July 14, 1953 c. H. wRoBEL.

REDUCING AND ENLARGING MACHINE FOR DRAFTSMAN AND DESIGNERS Filed Feb. 6. 1952 2 Sheets-Sheet 2 INVENTOR Ca/LH WeoBEL,

ATTORNEY Patented July 14, 1953 UNITED .STATES PATENT orrlci-:TT T

. RDUCING AND ENLARGIN G MACHINE FOR DRAFTSMAN AND DESIGNERS Carl H. Wrobel, Detroit, Mich.

Application February 6, 1952, Serial No. 270,150 3 claims. (C1. 3323 My invention relates to scaling instruments or machines used by draftsman and designers for reducing and enlarging drawings or the like.

The principal object of the invention is to provide a simple, lightweight and relatively inexpensive machine of this character which may be readily moved about the drawing room and quickly and easily applied to and removed'from drawing boards. i

Another object of the invention is to provide a device or machine of the above indicated character which, when in use, will have its parts so disposed that both the pattern or drawing being reduced or enlarged and the reproduction thereof will be close to each other and in the direct sight of the user of the instrument.

Another object is to providea machine of this character which is pivotally mounted on the drawing board by a single pin of the thumbtack type which may be easily pushed into'the drawing board and as readily removed.

With the above and other objects and advantages in view, the invention resides in the novel combinations and arrangements of parts and the novel features of construction hereinafter described and claimed, and illustrated in the accompanying drawings which show the present preferred embodiment of the invention.

In the drawings:

Fig. 1 is a front elevation of my improved reducing and enlarging machine with parts broken away;

Fig. 2 is a top plan view with the parts positioned as shown in Fig. l;

Fig. 3 is a cross section on an enlarged scale taken on the line 3-3 in Fig. 1 looking in direction of the arrows;

Fig. 4 is a similar cross section on the line lI-d of Fig. 2;

Fig. 5 is a similar cross section on the line 5--5 of Fig. 1; and y Fig. 6 is a diagram showing the use of the ma chine.

In Fig. 1 the improved reducing and enlarging machine, designated as a whole by the numeral I0, is shown positioned on a sheet of paper P applied to a drawing lboard D. The instrument Iil comprises a main body member or block II which is pivoted to the board to swing about a xed pivot point A and through which extend two parallel rack bars I2 and I3 simultaneously slidable in the same direction but at diiferent ratios of movement. The rearmost and slower moving rack bar I2 carries at one end a marker block or member I4 which travels along the the l Il

other rack bar I3 and carries a marking point B in the form of an open notchadapted to rreceive the point of a pencil so that a dot or mark may be made on the paper. The foremost and `faster moving rack bar I3 has at its corresponding end `a tracer arm I5 with a point C which is moved over the pattern or drawing that is to be reduced. In the embodiment of the invention illustrated the two rack bars are moved in a ratioof twoV to one by small and large gears I6, I'I xed toa shaft I8 journaled in the body I0, the two gears being in mesh with the teeth of the bars I2, I3 respectively. Thus when the tracer lpoint C is moved toward or from the pivot Ay apredetermined distance, the marker point or notch B will be moved one half of that distance in the same direction. It will be noted upon reference to Fig. 2 `that the points A, B and() are in perfect alignment lengthwise of the device, and that they are disposed forwardly of the body and the rack-bars. Hence the user will have a lClearview ofv both of the drawings which willxbe closely adjacent to each other because the points Band C are carried i by the corresponding ends of rack bars that move inthe same direction.

The body member II is of generally rectangular shape having a flatfbottom to slidek on the paper or like sheet P. In its top are upwardly open longitudinal guide channelsA 20 and 2I"'to slidably receive the rack bars I2 and I3 respectively.. These bars have their teeth on their '.upper edges and are retained'in the channels by the disposition of the gears lI 6, I'I immediately above them as seen in Fig.' 3. Projectingforwardly from the front wall of the body' II isa at arm 22 disposed in contact with the paper and formed with a hole 23 toreceive a'thumbtack-like pinv24 having a cylindrical head or flnger piece 25 at its top. The'pin 24 is pushed into the drawing boardto attach the device to the latter, and it formsthe pivotal axes A about which the device swings. The arm 22v projects at an angle so` as to dispose the holer23 in the plane of the outer end of the body II. 'While' the bodyk II may be made in one piece,"1 have shown it formed of a front plate 25, a back plate 2l, three intermediate plates or blocks 28, 29, 3) and a bracket plate 3|, these upright plates being fastened together by' two or more ,machinev screws 32 or by other suitable means.`r The arm 22' fis formed integral with the bracket plate 3I. The

other plates form the Aguide channelsj20 and as seen in Fig.3. Thev'side plates 2B"and 2T have upwardly extending ears'formed with alined bearing openings forthze jends of the `shaft .fllandf serve as shields or guards for the two gears which are fixed to the shaft by pins as shown or otherwise.

The traveling marker member I4 is also in the form of a rectangular or square block with a lat bottom to slide on the paper. It thus supports the extended portions of the rack bars and assists in holding them parallel with each other and the drawing board. In the top of the block or meniber I4 are two longitudinal channels 33 and 34 which receive the bars I2 and I3 respectively. The rack bar I2 has its right hand end removably fastened in the channel 33 by a pin 35 with a finger piece or loop 36 at its outer or rear end. The rack bar I3 is slidable in the channel 34 and is retained therein by a rectangular guide strip 31 disposed over the teeth of the rack bar and filling the upper portion of the channel, the strip or bar 31 being removably secured in position by one or more screws 38. may be variously constructed, it is shown as coniposed of a front plate 39, a rear plate fill, three intermediate plates 4I, 42, 43 and a bracket plate 45, all fastened together by screws 43. The bracket plate is right angular having at its bottom a forwardly projecting flat portion 4'.' which slides on the paper. The portion or Flange 41 is rectangular and of the same length as the block I4 as seen in Fig. 2. On the outer or right hand edge of the ilange 41 is a projection 453 and o at the juncture of the forward edge of the projection and the outer edge of the flange is a notch 49 of a size to receive the point of a lead pencil. This notch forms the above mentioned point B.

The tracer arm I5 is vertically disposed and of rectangular shape in cross-section so that one of the corners of its lower end forms the point C. The arm I5 depends from the forwardly projecting portion 50 of a right angular member 5i. The longitudinally extending portion of the latter is disposed in overlapping engagement with the outer or right hand end of the rack bar I3 to which it is detachably and adjustably secured. As shown in Fig. l, the portion 5I has on its bottom teeth to engage the teeth of the bar I3, and these interengaged and overlapped portions are disposed in a rectangular passage 52 extending longitudinally through a combined clamping and supporting member 53. The latter is in the form of a vertically disposed rectangular block with a flat bottom slidable on the paper so that it forms a supporting leg for the outer end of the rack bar I3. A thumb screw 54 is disposed in a threaded hole in the top of the member 53 to force the overlapped portions of the bars I3 and 5I downwardly to clamp them ln the opening 52. If desired a thin metal strip or shim may be positioned in the top of the opening 52, as shown in Fig. 1, for the end of the set screw 54 to thrust against. Also if desired the overlapped portions of the bars I3 and 52 may be connected by a pin 56 to prevent any endwise movement of one bar relative to the other.

To prevent the rack bar I2 from being pulled out of the body II I provide a stop 51 at the inner or left hand end of that bar for engagement with the corresponding end of the body. Such stop may be in the form of a block positioned on the bar I2 and fastened by a pin. On the bottom of the stop block may be formed teeth to mesh with those on the rack bar. To permit the device to be shown on a larger scale on the drawings, parts of the two rack bars have been omitted. While the device may be made in var- While the block I@ u ious sizes, I have obtained good results in quickly reducing drawings by a device having an overall length of about 40, a width of 1%, and a height of 2", and weighing only 2%. pounds. The device has been described as a reducing instrument but for enlarging the procedure would be reversed between points B and C. It is also to be understood that the ratio of movement of the rack bars may be changed by varying the ratio of the two gears. The machine may be sold in sets of different ratios, but when a machine of the described ratio has been used to reduce a drawing to one half scale, the operation may be repeated on the half scale drawing to obtain a quarter scale drawing, etc.

From the above detail description it is believed that the use and operation of the machine will be understood and especially in connection with the diagram shown in Fig. 6. In this view the body II with its arm 22 swings about the pivotal axis A, the pin 24 in the drawing board, when the tracer arm I5 is shifted to move the point C to diierent places or point on the large view at the right in Fig. 6 which is to be reduced one half. When the point C is at each of the places or points a pencil is used to make a dot in the notch B. The various dots are then connected to make the reduction shown.

From the foregoing, taken in connection with the accompanying drawing, it will be seen that novel and advantageous provision has been made for carrying out the objects of the invention, and while preferences have been disclosed, attention is invited to the possibility of making variations within the scope of the invention as claimed.

I claim:

l. A light-weight portable scaling instrument for draftsmen and designers comprising a pair of parallel rack bars having teeth on their upper surfaces, an upright body of rectangular shape having in its top upwardly open longitudinal channels in which said rack bars are slidable, a pair of opposed bearing ears projecting upwardly from the front and rear sides of said body, a shaft journaled in said ears and having fixed thereto a pair of gears of different ratios for engagement with the teeth of the respective rack bars to slidably retain the latter in their channels, an arm projecting forwardly from said body and having a hole to receive a pivot pin insertable in a paper covered drawing board to pivotally mount the body with said rack bars extending beyond one end of the latter, means spaced horizontally from said one end of the body to support said extended ends of the rack bars, said means including an upright block provided with a ilat base to slide on the paper on the drawing board and with a guideway in its upper portion through which one of said rack bars extends and is slidable, means removably fastening the other of said rack bars to said block, a horizontal flange projecting forwardly from the lower portion of said block and having a notch to receive a pencil point, and a member carried `by the end of said rack bar which extends beyond said block and provided with a pointer, said hole, notch and pointer being longitudinally alined.

2. The structure of claim 1 in which said body includes front and rear side plates and an intermediate portion, said side plates forming portions of said channels and having said bearing ears on their upper edges, and means for detachably fastening said side plates to said intermediate portion.

3. The structure of claim 1 in which said memt 5 ber is a bar of right angular form with one of said pointer and the extended rack bar which its arms projecting forwardly and then downcarries it. n wardly to form said pointer and its other arm CARL H. WROBEL.

projecting longitudinally in overlapping contact with the rack bar extending from said block, to 5 References Cited in the me Of this Patent gether with a second upright block having 'in Y UNITED STATES PATENTS its upper end a passage to receive said overy Number' Name e Date lapping portions of the right angular member Y 1 and its associated rack bar, anda set screw for 1359'250 Albee, Alle. 10, 1920 removably clamping said overlapped portions in 10 FOREIGN PATENTS said passage, said second block having a flat bottom to Islide on the drawing paper and support Nunu Greg? l'ela 791,503 France Sept. 30, 1935 

